Response of Black Bears to Forest Management in the Southern Appalachian Mountains

Abstract

We evaluated responses of black bears ( Ursus americanus) to changes in habitat in the Pisgah National For- est in North Carolina, USA. Changes in habitat were due to forest management, which affected bear habitat in complex ways. Harvested stands provided plentiful food resources that decreased with regeneration of the canopy. However, their value was offset by a lack of resources associated with mature overstory. Following canopy closure, early-successional food resources in harvested stands tended to decrease, although some soft mast remained more abundant than in unharvested stands. We used a tested Habitat Suitability Index (HSI) to evaluate effects of har- vest management on bear habitat. Values of HSI for harvested stands tended to differ little among young stands and older stands regenerating in pine (Pinus spp.) or hardwood, and all had lower HSI values than unharvested stands. Although effects of roads are modeled negatively in the HSI, proximity of harvested stands to logging roads did not bias comparisons to harvested stands. We used time-series analysis to characterize year-to-year changes on HSI maps for our study area from 1981 through 1994, and designated the results as an index of habitat change. We used this index to evaluate use of changed areas by black bears, estimated from 127 home ranges. Adult females used changed areas inversely proportional to the index of change, whereas adult and juvenile males showed no preferences. With respect to year-to-year variation at the peripheries of their home ranges, adult males and adult females selected habitat patches where suitability had increased and rejected patches where suitability had declined. Home ranges of adult males contained proportionally fewer areas of habitat decline than those of females or juvenile males. Adult females used areas where habitat suitability decreased, proportional to the decrease, but did not prefer them to areas of stable or improved suitability. Adult males appeared to avoid areas of decreased suitability altogether. Forest management positively affected some aspects of bear habitat but had an overall negative effect on habitat suitability in the southern Appalachians. Forest management will not improve bear habitat overall in areas where resources are abundant. Where soft mast is limiting, however, trade-offs between overall habitat suitability and improved productivity of soft mast may be warranted.